Oxtail is very good. And it used to be a cheap meat. Not anymore. If you can find it, it'll cost you five or six bucks a pound. And it's largely bone. Of course, a cow only has one tail...
As for liver, it can be good, too. Calf's liver is better. Probably the best way to serve it is the Italian version of liver and onions:
Put the liver in the freezer for about half an hour, or however long it takes to begin to firm up. Take it out and slice it very thinly. Maybe an eighth of an inch thick; between that and a quarter of an inch, at least.
Put the liver in a bowl and cover with milk and let it sit for an hour or so; that will tame some of the funky flavor.
Meanwhile, peel a couple of big sweet onions and cut them in half vertically. Slice each half thinly, into half-rings.
Throw the onions into a big skillet with olive oil, salt, and cook over moderate heat till they wilt and cook through. Push to one side, add the liver, and raise the heat to high. Add salt and pepper to the liver, and cook very quickly on both sides. If you overcook it, it'll toughen. It shouldn't take more than a few minutes. While it's cooking throw in a splash of white wine and reduce.
Mix with the onions. Venetians would eat it with polenta. You could do that, or perhaps choose rice.
